Brush assembly for an electric motor

Abstract

A brush assembly has a brush, a brush cage, and a spring. The spring is a constant force spring having two coil portions and a connecting portion. The connecting portion the brush are together received in the brush cage. The brush has a contact end arranged to make sliding contact with a commutator and a second end remote from the contact end against which the spring applies its force, to urge the brush out of the brush cage. A hook is formed at each of two opposite sides of the brush cage, at a first end portion of the brush cage adjacent the contact end of the brush. The coil portions respectively engage the hooks. The hooks extend at different angles to a corresponding outer surface of the brush cage.

The invention claimed is: 
     
       1. A brush assembly comprising a brush, a brush cage, and a spring,
 wherein the spring comprises two coil portions and a connecting portion interconnecting the coil portions, the connecting portion of the spring and the brush being received in the brush cage, 
 the brush comprises a contact end and a second end remote from the contact end, the connecting portion of the spring abutting against the second end of the brush, 
 a hook is formed at each of two opposite sides of the brush cage, at a first end portion of the brush cage adjacent the contact end of the brush, 
 each of the two coil portions is connected with a corresponding one of the hooks, and 
 each of the hooks extends at a different angle to a corresponding outer surface of the brush cage, 
 
       wherein the hooks comprise a first hook and a second hook,
 each of the hooks comprises a stop plate extending outwardly from the brush cage and a hook portion disposed at a distal end of the stop plate, 
 an angle A is formed between the stop plate of the first hook and the outer surface of the brush cage, 
 an angle B is formed between the stop plate of the second hook and the outer surface of the brush cage, 
 the angle A is not equal to the angle B, and 
 the angle A and the angle B are both greater than 90 degrees but less than 180 degrees. 
 
     
     
       2. The brush assembly of  claim 1 , wherein the absolute value of a difference between the angle A and the angle B is greater than zero degree but less than 30 degrees. 
     
     
       3. The brush assembly of  claim 1 , wherein the angle A is 120 degrees, and the angle B is 105 degrees. 
     
     
       4. The brush assembly of  claim 1 , wherein the brush cage comprises two sidewalls, and each stop plate extends from a corresponding one of the sidewalls at the first end portion of the brush cage. 
     
     
       5. The brush assembly of  claim 1 , wherein a cutout is formed between each stop plate and the corresponding hook portion. 
     
     
       6. The brush assembly of  claim 1 , wherein the spring is a constant-force spring. 
     
     
       7. A motor comprising a stator and a rotor, the rotor comprising a commutator and a winding electrically connected with the commutator, wherein the motor further comprises the brush assembly of  claim 1 , the contact end of the brush of the brush assembly making sliding contact with the commutator to supply power to the winding.